Generally, the bearing body of a linear ball bearing is made by forming an axial generally trapezoidal recess in a rectangular steel block and then, by forming a symmetrical hook-shaped supporting part by cutting off the lower part of the trapezoidal recess in the shape of an equilateral triangle.
(Japanese Patent Laid-open No. 55-109820/1980).
Thus, the workpiece of the bearing body is made by forming a through hole of a particular shape in the central part of the steel block by turning and a turning process to cut of the lower part of the central part.
Therefore, degradation in profitability due to increased material cost owing to production of chips in the turning process, increased time for processing and increased cutting oil consumption are the factors of a high cost. Such a process is inefficient.
Retainers incorporated into the bearing body are made of steel plates in a necessary shape by press forming.
(Japanese Patent Laid-open No. 54-145837/1979)
In press-forming a steel plate into the retainer, axial slits are formed at necessary parts and relatively small tongues are formed for scooping up the balls so as to project in the front and the rear of the slits, therefore, substantial strength and a high wear resistance are required of the tongues.
Therefore, it is necessary to use a steel plate of a high toughness and to heat-treat the steel plate after the forming process.